1. Field
This disclosure relates to a random copolymer capable of forming a neutral surface, and methods of manufacturing and using the same. In particular, disclosed is a random copolymer capable of stably attaching to a substrate or particles and rapidly forming a neutral surface on which a block copolymer can be stably arranged, and a method of manufacturing the same.
2. Description of the Related Art
Block copolymers composed of two or more different homopolymers or monomers whose ends are bound to each other can self-assemble to form periodic structures having a size of several tens of nanometers. In order to achieve the self-assembly, the block copolymers require a driving force. When the block copolymers are treated with various driving forces from techniques such as thermal annealing (e.g., in a vacuum or in the atmosphere of an inert gas such as nitrogen or argon), infrared annealing, laser annealing, or solvent vapor-assisted annealing, phase separation occurs between two or more block components of the block copolymers, resulting in self-assembly of the block components into a regular pattern having repeating structural units. In particular, a diblock copolymer may include two monomers A and B having different chemical properties, which may be represented by “A-b-B.” In the case of the diblock copolymer, when phase separation between the different block components A and B is caused in the copolymer, self-assembled periodic patterns including repeating structural units such as spheres, cylinders, lamellae and perpendicular lamellae can form. Ultrafine patterns having a size of several tens of nanometers may be formed using the self-assembly of block copolymers, and the technique can be applied to semiconductor devices and liquid crystal display panels, all of which use ultrafine patterning.
A neutral layer having a neutral surface, on which block copolymers can be easily self-assembled at a large scale into perpendicular lamellae or perpendicular cylinders, is desired for forming an ultrafine pattern. Such a neutral layer is a layer that is non-preferentially wetted with respect to any block, for example one of blocks A and B from the diblock copolymer A-b-B. A surface of the neutral layer has substantially the same surface affinity to the other block components of the block copolymer. Therefore, such a surface is referred to as a neutral surface or non-preferential surface.
Currently available neutral layers are annealed for approximately 6 hours to approximately 24 hours to form the neutral layer. The annealing time used to form such a neutral layer degrades desirable properties, resulting in a loss of productivity and processability in the manufacture of a neutral layer or a nanopattern substrate. Therefore, there remains a need for an improved random copolymer to provide a neutral layer with improved properties.